Application of Lean Six Sigma in Construction Project Management: Reducing Delays and Cost Overruns

This paper assesses how Lean Six Sigma (LSS) approaches reduce the delays, cost increase and optimise the workflow and stakeholder coordination in construction projects. An integrative and systematic review has been utilised for transparency and methodological rigour. Following the screening of 321 studies in four major academic databases, 49 peer-reviewed articles published only in 2014 to 2025 were selected to be included in the final synthesis. These researchers found results of construction situations in different parts of the world where construction was done covering commercial, infrastructural and residential constructions. Before intervention, the projects were experiencing average cost overruns of 18 per cent and delays of 22 per cent. Lean tools, including Value Stream Mapping (VSM), Last Planner System (LPS), 5S, Just-in-Time (JIT) delivery, and Kaizen, along with the use of the Six Sigma framework, DMAIC, significantly enhanced the results of project outcomes. Delays were reduced to 7 per cent and cost overruns were reduced to 6% which constituted improvements of 68 per cent and 66 per cent, respectively. Case studies also proved the efficiency of LSS. A commercial project in the United States not only decreased schedule variance by 30 per cent, but also a highway project in India decreased material costs by 20 per cent, and a housing project in Malaysia decreased defects by 40 per cent. LSS helped to decrease the non-value-added activities by 40 per cent, labour productivity, and the level of stakeholder satisfaction by 30 per cent as well. Irrespective of these developments, some problems include cultural resistance, lack of training and quality of data. Having firm leadership, lifelong learning, and strategic digital implementation are the key success factors to maintaining the LSS advantages in construction management. The results show that Lean Six Sigma may be a useful model in the reduction of inefficiencies, which provide relevant suggestions that can be used by project managers to improve time and cost management of construction projects.